I recently built my own CNC router. With the recent discussions of the 4' x 4' CNC Router parts and Fine Line Automation Saturn machines, I thought that some may be interested in a similarly sized DIY machine not built from a kit. I was in the same position of some of you and could not afford an assembled or even kit based machine.
My machine has a cutting area of 49" x 60", and It is designed so that I can hold a full sheet of MDF or Melamine (at 49" x 97" they are slightly larger than plywood sheets). It is relatively easy to index what you are cutting and slide the sheet to work with stock larger than your nominal cutting area. If my shop was big enough I would have made it long enough to handle the full sheet without indexing. That said, most of the projects I foresee making will be easily accommodated by the size it is without indexing.
My router is made from two sizes of 8020 brand extrusions, 80x160mm (which is the biggest 8020 makes, I believe) and 80x80mm, along with some flat and angle stock. These extrusions are extremely stout and larger than I have seen in most kits. I lucked into buying this as surplus and got it at a bargain price, $1 per pound - normally these size extrusions would go for $2- $3 per inch. Bargain hunting is key to saving money on DIY builds! All of my frame and structural materials came out to a little less than $600, maybe another $100 in fasteners. The extrusions would cost about $2500 to buy new at 8020's online prices (not including shipping).
The machine weighs more than 400 pounds, and is built almost entirely of aluminum. Most parts I used at the size I found at the surplus yard. I did not need to have any parts machined - any cuts needed were cut by me using standard woodworking tools such as a radial arm saw and a drill press. Most assembly holes were match drilled with a handheld drill.
My CNC router is my own design and has several unique features. While it normally has 5" clear between spoil board and lowest point on gantry, it is designed so the entire gantry can be easily raised steplessly to provide clearance up to 12 inches. I know of no other designs with this engineered-in flexibility in gantry height. My Z axis has 7" of travel, with a bit projecting 2" from collet, I can raise the end of the bit flush with bottom of gantry. It also has a very unique Y-Z carriage design that maximizes the spacing of the bearing assemblies and minimizes the cantilever of the spindle. Instead of heavy plates it is all made from very stiff yet light aluminum angle. My unique design avoids the large spindle cantilever I see as a weakness in virtually every commercial machine. My spindle axis is only about 3" from the gantry.
Electronics wise I used good, but definitely not industrial grade components - ethernet smoothstepper, Gecko G540 stepper driver, low inductance 420 oz in NEMA 23 steppers (4) from CNC Router Parts. I used fully supported SBR type linear guides all around, rack and pinion for X and Y axis and a ballscrew for Z. I have tested it up to 1000 ipm rapids (I have it set in Mach at 600 which is plenty fast enough for me). My normal cutting speeds are usually in the 180 - 200 ipm range. It has a 2.2kw water cooled spindle, with the computer starting, stopping and controlling spindle speed via g-code (via PWM 0-10V control using the G540, no modbus needed).
My electronics are all mounted to the back side of the gantry - no complicated cable chains - far shorter wiring runs and no damage to cable due to repetitive flexing. I see so many people with complicated electronics, my box is only about 15 x 4 x 8. It has a plexiglas cover so I can see all the status LEDs. Even my VFD is mounted to the gantry. A single Ethernet cable runs from the computer to the cnc, run up the wall, across ceiling and down to the gantry with enough slack to cover travel range.
Software wise, I use Mach4 as the control software ($200). Mach3 is more widely used and well supported, but is basically end of life. Mach4 is fully functional now and still being actively developed. If I had heard of UCCNC before setting up the computer, I probably would have gone with that. Several people I respect on CNCZONE recommend it and it is cheaper ($60).
While I have quite a few friends using various Vectric software titles, and they are good, Vectric is not the only game in town. It was too pricey for my budget. Autodesk Fusion 360 is a full 3d CAD package (including CAM to generate your g-code!) that is available FREE to students OR startups (including hobbyists) making less than $100k per year. Far more capable than sketchup, (even the Pro version) it is a great bargain. I use it for mechanical type designs.
Autodesk ran a one day special at the end of January and I got a full year of ArtCAM Standard for $99! While I hate "renting" software, the low entry price for near Aspire level capabilities made it a no brainer. They currently (thru July 31, 2017) have it at $180 for a year. I use ArtCAM for artistic type projects.
ArtCAM and Fusion 360 run on a separate, more powerful computer in the house. Gcode file are transferred via USB stick - the cnc control computer is not online to preclude unwanted updates or interruptions.
All in, I only spent about $2700 on my machine, including the brand new HP all in one computer with Windows 10 (dedicated only to running Mach4 to operate CNC) and software. It is fast, strong, and I understand every part of it. I think it is stronger, and faster than the $18,000 Legacy Maverick that several people I know have (it does not yet have the rotary axis of the Maverick, but it will!). I purposely built it bigger than the Maverick which only does 36" x 60", just to have bragging rights over my friends.
I would recommend building your own machine, if and only if, building it would be an enjoyable project on its own for you. For me it was, and due to getting some bargains, I ended up with a far better machine for the price than I have seen anywhere, so it definitely can be a good way to go. From what I have seen out there, even if I bought the extrusions new, my machine would compete price and performance wise with anything of similar size.
2.0 could build the all aluminum router he'd like AND insulate the shop - the extrusions I bought are still available in Northern Colorado - not too far of a drive to save a couple thousand $. The supplier is motion control surplus - they are also a hiwin distributor - pick up your guide rails in person at the same time and save a lot on shipping.
I welcome any questions or feedback.